The present invention deals with the problem of winding and/or unwinding two-dimensional web materials onto or from a corresponding sleeve designed for this purpose, for example, webs made from paper, plastic, metal foil or similar material. In this case, it is necessary that the sleeve is slid in the axial direction onto shaft means, for example, either a mandrel or a clamping shaft, and is effectively connected by means of a suitable clamping means in such a way that the sleeve together with the mandrel or the clamping shaft are effectively connected around a common longitudinal axis.
For the purpose of clamping means for winding and/or unwinding a two-dimensional web onto a shaft or the like, clamping devices are generally known. For example, in a first variant at the outer shell of a bracing tube, which is rotatable around the longitudinal axis of said tube, are provided several grooves which are distributed in the circumferential direction and run in the longitudinal direction, said grooves being designed to accommodate hoses. Alternately, in a second variant, a single hose is placed in the axial direction into the inside space of the bracing tube, while the hoses are so changed in their outside diameter as a result of being filled with suitable medium, that the pressure elements, which are connected with the outside hoses or the hose located inside the bracing tube, are pressed radially toward the outside and as a result can be engaged by way of clamping with the inside wall of the sleeve.
Taking into consideration the limited clamping force which can be achieved with these known clamping devices, they have a limited field of application. Also, the designs of the bracing tubes, which are provided with outer grooves or with individual openings for the pressure elements, are relatively costly. Furthermore, hoses used in these devices, in particular the hoses provided at the outer diameter, are relatively susceptible to defects.
With a clamping device according to European Patent A 0 413 890 the sleeve is engaged with a supporting body by means of a number of axially and radially adjustable sliding elements, which rotates around its own axis, while the sliding elements in each case are placed in a guideway of a cylinder core, said guideway being developed as an inclined plane, which is movable by a piston/cylinder unit in the axial direction relative to the supporting body and, as a function of the direction of motion, in each case said sliding elements are adjusted radially toward the outside or inside together with a clamping element placed thereon.
In view of the foregoing, the present invention provides an improvement of devices for clamping a sleeve placed onto a tube for winding and/or unwinding a two-dimensional web in that, while maintaining a secure clamping, the structural design of the individual elements is considerably simplified and the clamping elements provided at the tube are easily accessible and, if required, can be replaced without incurring special expenditure.